| 摘要 |
PURPOSE:To keep a bias voltage constant by using a current mirror circuit to cancel the change in a bias current due to the change in a power voltage. CONSTITUTION:A collector of a PNP transistor(TR) 7 of a current mirror circuit 10 is connected to a connecting point between an emitter of a TR Q3 and the 1st bias setting resistor Ra and the other terminal of the 1st bias setting resistor Ra is connected to a collector of an NPN TR 7' of a current mirror circuit 10'. A positive power voltage supply terminal 1 is connected to a connection point of resistors 2, 3 via a capacitor 9 and a resistor 8 connected in series, and a negative power voltage supply terminal 1' is connected to a connection point of resistors 2', 3' via a capacitor 9' and a resistor 8' connected in series. Thus, the change in a bias current IB due to the change in a power voltage Vcc is cancelled.
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